Reference is now made to FIG. 1 which illustrates a prior art diamond-shaped sensor pattern 100 for use in a capacitive touchscreen. The sensor pattern 100 includes a first set of diamond-shaped sensors 102, often referred to in the art as the “Yforce” or transmit electrode structure. The sensors 102 are arranged in a matrix such that sensors 102 in each column are connected to each other by a connecting member 104. The sensors 102 in adjacent columns are isolated from each other. The sensor pattern 100 also includes a second set of diamond-shaped sensors 112, often referred to in the art as the “Xsense” or receive electrode structure. The sensors 112 are arranged in a matrix such that sensors 112 in each row are connected to each other by a connecting member 114. The sensors 112 in adjacent rows are isolated from each other.
The matrix of the diamond-shaped sensors 102 is interleaved with the matrix of diamond-shaped sensors 112 in a manner where the space between a group of four diamond-shaped sensors 102 is occupied by one of the diamond-shaped sensors 112, and the space between a group of four diamond-shaped sensors 112 is occupied by one of the diamond-shaped sensors 102.
In some embodiments, the first and second sets of sensors 102 and 112 and connecting members 104 and 114 are made of a single patterned material layer, wherein connecting members 104 provide bridged connections to sensors 102 over the connecting members 114, or connecting members 114 provide bridged connections to sensors 112 over the connecting members 104. In other embodiments, the sensors 102 and connecting members 104 are made of a first patterned material layer, and the sensors 112 and connecting members 114 are made of a second patterned material layer. In the embodiments discussed herein, the material layers may comprise relevant materials known in the art such as, for example, indium tin oxide (ITO), and may be supported by a transparent substrate layer.
In embodiments wherein the sensor pattern comprises multiple material layers, the first and second patterned material layers are isolated from each other by an interposed insulating layer. The first patterned material layer including diamond-shaped sensors 102 and connecting members 104 may comprise the lower layer of the capacitive touchscreen, and the second patterned material layer including diamond-shaped sensors 112 and connecting members 114 may comprise the upper layer (as shown in FIG. 1), or vice versa. The insulating layer, first patterned material layer, and second patterned material layer are supported by a transparent substrate layer.
The prior art diamond-shaped sensor pattern described above typically overlays a display screen in a stacked configuration. Commonly, that display screen is a liquid crystal display (LCD) although other display technologies may also be used. In operation, these prior art diamond-shaped patterns can suffer from an unacceptable amount of noise captured from the underlying LCD display screen. Additionally, there is room for improvement with respect to sensitivity of the prior art diamond-shaped sensor patterns to capacitive touches (or proximity detections), particularly when an object having a small contact surface area, such as an active or passive stylus, is used to interface with the capacitive touchscreen. Furthermore, as touchscreen panels are manufactured to be increasingly thinner, performance is increasingly affected by the design and shape of the sensor pattern, both in single layer and multi-layer stack configurations.
Although some custom touch sensor patterns exist, such designs typically suffer in thin stack arrangements, particularly with regard to performance, pattern visibility, and ITO manufacturing. A need accordingly exists in the art for improved sensor patterns for use in single layer and multi-layer stack configurations of capacitive touchscreens.